Properties of hyperons in chiral perturbation theory

TL;DR

This paper discusses advances in chiral perturbation theory for hyperons, addressing convergence issues, including decuplet resonances, and achieving model-independent results for hyperon properties relevant to CKM matrix element determination.

Contribution

The authors develop a covariant, analyticity-preserving renormalization scheme that improves convergence and systematically includes decuplet resonances in hyperon chiral perturbation theory.

Findings

Improved convergence using a new renormalization prescription.

Successful inclusion of decuplet resonances in a consistent manner.

Model-independent results for hyperon magnetic moments and form factors.

Abstract

The development of chiral perturbation theory in hyperon phenomenology has been troubled due to power-counting subtleties and to a possible slow convergence. Furthermore, the presence of baryon-resonances, e.g. the lowest-lying decuplet, complicates the approach, and the inclusion of their effects may become necessary. Recently, we have shown that a fairly good convergence is possible using a renormalization prescription of the loop-divergencies which recovers the power counting, is covariant and consistent with analyticity. Moreover, we have systematically incorporated the decuplet resonances taking care of both power-counting and $consistency$ problems. A model-independent understanding of diferent properties including the magnetic moments of the baryon-octet, the electromagnetic structure of the decuplet resonances and the hyperon vector coupling $f_1(0)$, has been successfully achieved within this approach. We will briefly review these developments and stress the important role they play for an accurate determination of the Cabibbo-Kobayashi-Maskawa matrix element $V_{us}$ from hyperon semileptonic decay data.